Thermal and high magnetic field treatment of materials and associated apparatus

ABSTRACT

An apparatus and method for altering characteristics, such as can include structural, magnetic, electrical, optical or acoustical characteristics, of an electrically-conductive workpiece utilizes a magnetic field within which the workpiece is positionable and schemes for thermally treating the workpiece by heating or cooling techniques in conjunction with the generated magnetic field so that the characteristics of the workpiece are effected by both the generated magnetic field and the thermal treatment of the workpiece.

This is a divisional application of application Ser. No. 11/109,376,filed Apr. 19, 2005 now U.S. Pat. No. 7,161,124.

This invention was made with Government support under Contract No.DE-AC05-00OR22725 awarded by the U.S. Department of Energy toUT-Battelle, LLC, and the Government has certain rights to theinvention.

BACKGROUND OF THE INVENTION

This invention relates generally to the treatment of material foraltering characteristics of the material and relates, more particularly,to the means and methods for treating such materials.

The material-treatment processes with which this invention is to becompared include those which are carried out for the purpose of alteringand thereby improving characteristics (such as can include structural,magnetic, electrical, optical or acoustical characteristics) of thematerial being treated. Such processes (e.g. annealing processes) caninvolve the treatment of materials at temperatures which are less thanthe melting temperature of the material being treated so thatcharacteristics, such as the strength, durability or hardness, of thematerial are advantageously affected by the treatment.

It is an object of the present invention to provide a new and improvedapparatus and method for treating materials to alter characteristics ofthe material.

Another object of the present invention is to provide such an apparatusand method which can be used to achieve properties in a material whichhave not heretofore been obtainable.

Still another object of the present invention is to provide such anapparatus and method which can employ thermal treatment of the material,yet require less input energy than do many conventional thermaltreatment processes.

Yet another object of the present invention is to provide such anapparatus and method which can be efficiently utilized to processmaterials over a relatively broad range of material applications.

A further object of the present invention is to provide such anapparatus and method whose principles can be used in commercialapplications which might require large quantities of materials whosecharacteristics are desired to be altered.

A still further object of the present invention is to provide such anapparatus which is uncomplicated in structure, yet effective inoperation.

SUMMARY OF THE INVENTION

This invention resides in an apparatus and method for alteringcharacteristics of a workpiece which includes an electrically-conductivematerial.

The apparatus of the invention includes means for generating a magneticfield within which a workpiece whose characteristics are desired to bealtered is positionable. In addition, the apparatus includes meansassociated with the magnetic field-generating means for thermallytreating the workpiece in conjunction with the generated magnetic fieldso that the characteristics of the workpiece are effected by both thegenerated magnetic field and the thermal treatment. The means forthermally treating the workpiece can include means for heat-treating theworkpiece, means for cooling the workpiece or both heat-treating meansand cooling means.

The process of the invention includes the steps which are carried outwith the apparatus of the invention. In particular, the process includesa step of exposing the workpiece to a magnetic field and thermallytreating the workpiece in conjunction with the exposure of the workpieceto the magnetic field so that the characteristics of the workpiece areeffected by both the magnetic field and the thermal treatment. Dependingupon the desired characteristics of a workpiece to be treated with thisprocess, the thermal treatment step can involve heating the workpiece orcooling the workpiece or both heating and cooling the workpiece inpreselected sequences, and such heating and/or cooling of the workpiececan be carried out before, during or after the exposure of the workpieceto the magnetic field.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevation view, shown partially cut-away, ofan embodiment of an apparatus with which a process of the presentinvention can be carried out.

FIG. 2 is a schematic side elevation view, shown partially cut-away, ofanother embodiment of an apparatus with which a process of the presentinvention can be carried out.

FIG. 3 is a schematic side elevation view of still another embodiment ofan apparatus with which a process of the present invention can becarried out.

FIG. 4 is a view illustrating in block diagram form an exemplary controloperation of an apparatus within which features of the apparatus of thepresent invention are embodied.

FIG. 5 is a light micrograph photo illustrating the microstructure of asample workpiece following thermal treatment which did not involveexposure of the sample to a high magnetic field.

FIG. 6 is a light micrograph photo illustrating the microstructure of asample workpiece following thermal treatment which also involvedexposure of the sample to a high magnetic field.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Within the illustrated drawings discussed herein, there are illustratedvarious examples of apparatus, or systems, with which a workpiece can beworked upon, or treated, so that characteristics (such as can includethe structural, magnetic, electrical, optical or acousticalcharacteristics) of the workpiece are altered. As will be apparent, eachof the exemplary apparatus described herein involves the exposure of aworkpiece to a magnetic field and to an associated thermal treatment sothat the characteristics of the workpiece are effected (i.e. altered) byboth the magnetic field and the thermal treatment to which the workpieceis exposed.

It will be understood, however, that in the interests of the presentinvention, as long as the thermal treatment (e.g. cooling or heating ofthe workpiece or both) are carried out in the same process involving theexposure of the workpiece to a magnetic field, it does not matterwhether the thermal treatment of the workpiece and the exposure of theworkpiece to a magnetic field occurs simultaneously. For example, inorder to provide a workpiece with advantageous properties or qualities(e.g. as may relate to strength, durability or hardness of theworkpiece), it may be desirable to initially raise the temperature ofthe workpiece to an elevated level, then expose the workpiece to amagnetic field, and subsequently remove the workpiece from the magneticfield and rapidly cool the workpiece to room temperature. Alternativetreatment processes may involve a repetition of heating and coolingcycles while the workpiece is advanced into, through, and then out of amagnetic field. Accordingly, the principles of the present invention canbe variously applied.

Considering first FIG. 1, there is illustrated an embodiment of anapparatus, generally indicated 20, within which a workpiece 22 can beworked upon, or treated, to alter the characteristics of the workpiece22. In this connection, the apparatus 20 includes means, generallyindicated 24, for generating an ultrahigh magnetic field within whichthe workpiece 22 is positionable, means, generally indicated 25, forthermally treating the workpiece 22 in conjunction with the exposure ofthe workpiece 22 to the generated magnetic field. More specifically, thethermal treatment means 25 includes means, generally indicated 26, forheating (i.e. heat-treating) the workpiece 22 and means, generallyindicated 28, for cooling the workpiece 22. Through the use of theheating means 26 and the cooling means 28, the workpiece 22 can beheated or cooled, as desired (e.g. in a preferred or controlledsequence) either prior to, during, or following the exposure of theworkpiece 22 to the ultrahigh magnetic field generated by the magneticfield-generating means 24.

As suggested earlier and depending, for example, upon the desiredcharacteristics of the workpiece 22 following treatment, heat can beapplied to the workpiece 22 prior to its introduction into the generatedmagnetic field, while it resides within the generated magnetic field, orfollowing its removal from the magnetic field. Along the same lines,cooling (or quench) can be applied to the workpiece 22 prior to itsintroduction into the generated magnetic field, while the workpiece 22is present within the magnetic field or following its removal from themagnetic field. It therefore follows that the workpiece 22 can be heatedor cooled in any of a number of different sequences depending upon thedesired characteristics of the workpiece 22 following treatment.

Within the depicted FIG. 1 embodiment 20, the heating means 26 employsinduction heating equipment 27 for heating the workpiece 22. Accordinglyand in order for the workpiece 22, and in particular, the microstructureof the workpiece 22, to be affected by both the heating means 26 and themagnetic field generated by the magnetic field-generating means 24, theworkpiece 22 which is capable of being worked upon, or treated, with theapparatus 20 must include an electrically-conductive material. In otherwords, in order for the microstructure of the workpiece 20 be responsiveto the magnetic field generated by the magnetic field-generated means24, the workpiece 22 must contain or be comprised of material whichrenders the workpiece 22 electrically-conductive.

With reference still to FIG. 1, the magnetic field-generating means 24includes a magnet 30 which is in the form of a solenoid magnet 30 havinga core 31 and illustrated cross-sectional portions 32. It is within thecore 31 (and inside the portions 32) that a desired high magnetic fieldis generated. The magnet 30 can take the form of either a resistivemagnet, a permanent magnet, or a superconductor (e.g. cryogenic or ahigh temperature superconductor) magnet capable of achieving relativelyhigh levels of magnetic field strength. In addition, a hybrid magnetwhich utilizes a combination of the aforementioned magnet classes (e.g.resistive, permanent and superconductor) can be employed. In theinterests of the present invention, the terms “high” and “ultrahigh”used herein in conjunction with the strength of the magnetic fieldstrength generated by the magnet 30 for purposes of treating theworkpiece 22 is at least as high as about one Tesla. In practice anddepending upon the form of the magnet 30, the magnet 30 may be capableof generating a field strength as high as several tens of Tesla.

Depending upon the desired magnetic field treatment of the workpiece 22while positioned within the apparatus 20, the generated magnetic fieldmay remain ON (i.e. operate continuously) for as long as the workpiece22 is exposed to the magnetic field or be ramped up as the workpiece 22is advanced into the magnetic field. Therefore, the operation of themagnetic field-generating means 24 is preferably controllable in thisrespect.

The cooling means 28 of the apparatus 20 includes means, generallyindicated 36, for defining a passageway 38 within which the workpiece 22is positioned while the workpiece 22 is being worked upon within theapparatus 20. Within the depicted apparatus 20, the passageway-definingmeans 36 is in the form of an insulated guide tube 40 having an entranceend 42, an exit end 44 and an interior which extends between theentrance and exit ends 42 and 44 and which provides the passageway 38 ofthe passageway-defining means 36. The guide tube 40 can be constructedof any of a number of non-magnetic materials, such as ceramic or quartz,which are incapable of being affected by the magnetic field generated bythe magnetic field-generating means 24 and which is capable of holding avacuum which is desired to be drawn within the tube 40 for reasons whichwill be apparent herein.

The guide tube 40 of the depicted apparatus 20 is U-shaped in formhaving two legs 50, 52 and an arcuate section 54 joining the legs 50,52. With the tube 30 shaped in such a manner, the entrance and exit ends42 and 44 open out of the same side of the magnet 30. It will beunderstood, however, that the tube 40 can possess any of a number ofalternative shapes, such as that of a straight tube, in accordance withthe broader aspects of this invention. Moreover and is suggestedhereinafter, the guide tube 30 need not be non-magnetic for sometreatment processes.

As mentioned earlier, the heating means 26 of the apparatus 20 utilizesinduction heating equipment 27 for purposes of heat-treating theworkpiece 22. In this connection, the induction heating equipment 27includes a length of a copper tube 60 having two end sections 62 and 64and a coiled section 66 which is disposed between the two end sections62 and 64 and which is positioned about one leg 52 of the U-shaped guidetube 40. While copper is well-suited as the material of the tube 40because of its thermal and electrically-conductive properties, othermaterials (such as aluminum or stainless steel) could be used. Forpurposes of heating the workpiece 22 by the induction heating equipment27, the workpiece 22 is positioned within the leg 52 of the guide tube40 so that the workpiece 22 is disposed within the interior of the coilsection 66.

In addition, the end sections 62 and 64 of the copper tube 60 areconnected between the leads of an alternating current (AC) power source68 for directing an alternating current through the coil section 66 forpurposes of heating the workpiece 22 as the workpiece 22 is positionedwithin the leg 50 of the guide tube 40. The operating principles of aninduction heating coil are well known so that a detailed description ofsuch principles is not believed to be necessary. Suffice it to say thatby directing an alternating current through the coil 66 (i.e. betweenthe tube end sections 62 and 64), a varying magnetic field is createdwithin the coil 66 which, in turn, induces electromotive forces in theworkpiece 22. As a result of the created electromotive forces, eddycurrents are produced within the workpiece 22, and because the workpiece22 has an internal resistance to current flow, heat is generated withinthe workpiece 22 thereby effecting a rise in the temperature of theworkpiece 22.

Although the coil section 66 of the copper tube 60 is shown anddescribed herein as being formed in a solenoid configuration, the coppertube can possess an alternative configuration, such as a poloidalconfiguration.

As an alternative to heating the workpiece 22 directly, a susceptor (notshown) could be positioned about the workpiece 22 (e.g. in heat exchangerelationship therewith) so that the heating means 26 heats the susceptorwhich, in turn, heats the workpiece. The materials out of which such asusceptor can be constructed can include paramagnetic materials,non-ferromagnetic materials, or even ferromagnetic material. Furtherstill, an alternative guide tube for the FIG. 1 apparatus 20 could bepositioned outside of, rather than inside, the coil section 66 of theheating means 26.

The apparatus 20 also includes means, generally indicated 80, fordrawing a vacuum within the guide tube passageway 38. In thisconnection, the vacuum-drawing means 80 includes a vacuum pump 82 whoseinlet is appropriately connected to the tube passageway 38 so thatoperation of the vacuum pump 82 evacuates the interior of the passageway38 of atmospheric gas (i.e. air). In the depicted apparatus 20, theinlet of the vacuum pump 72 communicates with the interior of thepassageway 38 at a location adjacent the end of the leg 52 of theU-shaped guide tube 40. During operation of the apparatus 20, a vacuumis drawn within the guide tube passageway 38 after the workpiece 22 ispositioned within the passageway 38. By evacuating the passageway 38 ofair at the outset of a treatment process performed with the apparatus20, the likelihood that the surface of the workpiece 22 will oxidizeduring the treatment process is significantly reduced. In other words,by evacuating the passageway 38 of air at the outset of a treatmentprocess performed upon the workpiece 22, the workpiece 22 is less likelyto experience corrosion during its treatment with the apparatus 20.

With reference still to FIG. 1, the cooling means 28 of the apparatus 20includes means, generally indicated 90, for directing a cooling fluid(e.g. purge or quench gas) into the passageway 38 where it is permittedto come into contact with the workpiece 22. In this connection, there isprovided a source 83 of compressed purge gas, such as Argon, which isconnected to the passageway 38 by way of an appropriate conduit so that,when cooling of the workpiece 22 is desired, the purge gas can bedirected into the passageway 38 where it is exposed to the workpiece 22positioned therein for withdrawing heat therefrom. Furthermore, there isprovided a source 84 of compressed quench gas, such as helium, which isconnected to the passageway 38 by way of an appropriate conduit so thatwhen quenching (i.e. relatively rapid cooling) of the workpiece 22 isdesired, the quench gas can be directed into the passageway 38 where itis permitted to come into contact with the workpiece 22 for withdrawingheat therefrom.

During operation of the apparatus 20, the temperatures of the quench andpurge gases introduced into the passageway 38 can be controlled bycontrolling the internal pressure of the gases contained within thepassageway 38. To aid in the control of passageway pressure, there isprovided a pop-off valve 94 which is mounted upon the end of the leg 52of the U-shaped guide tube 40 which permits an amount of quench or purgegas to escape from the tube passageway 38, as necessary, to maintain theinternal pressure of the tube passageway 38 below a preselectedpressure.

It follows that within the apparatus 20, the workpiece 22 can be heatedor cooled, as desired, in conjunction with the magnetic field generatedwithin the core 31 of the magnet 30. For example, after positioning theworkpiece 22 within the leg 50 of the guide tube 40 and evacuating thetube 40 of atmospheric gas, the temperature of the workpiece 22 can beramped up to a desired level through, for example, a sequence oftemperatures with appropriate hold times at each temperature. The argongas can be used to accelerate radiation cooling as desired so that therate of the temperature being ramped is controlled. Similarly, thestrength of the magnetic field generated with the magnet 30 and to whichthe workpiece 22 is exposed can be ramped to a desired level andmaintained thereat for a desired duration. Finally, the workpiece 22 canbe quenched by a high volume of helium, and then the magnetic field isramped to a lower level. It will be understood that the treatmentschemes of the workpiece 22 with heat (from the heating means 26),cooling (from the cooling means 28) and magnetic field (from themagnetic field-generating means 24) of the apparatus 20 can be varied inany of a number of ways.

With reference to FIG. 2, there is illustrated an alternative embodimentof an apparatus, generally indicated 100, with which a workpiece 102 canbe treated in accordance with the steps of the present invention. Theapparatus 100 includes means, indicated 104, for generating a magneticfield within which the workpiece 102 is positionable and heating means106 (i.e. induction heating means) for heating the workpiece 102. Inaddition, there is provided workpiece cooling means, generally indicated108, which includes a passageway-defining means 110 providing apassageway 112 within which the workpiece 102 is positioned as it isworked upon by the apparatus 100.

Within the depicted apparatus 100, the magnetic field-generating means104 includes a solenoid magnet 113 having a core 114 which is definedinside of the illustrated cross-sectional portions 116 of the magnet113. The magnet 113 is capable of generating an ultrahigh magnetic fieldwithin its core 113, and it is within the core 113 that the workpiece102 is positionable. The passageway 112 is oriented substantiallyvertically and is supported substantially centrally within the core 114of the magnet 113 by way of a horizontally-oriented mounting plate 118,and the induction heating means 106 includes a copper tube 120 having acoil section 122 which encircles a section of the passageway 112disposed within the core of the magnet 113 and end sections 124 and 126which are connected to an AC power source by way of coaxial RF powercable 128 having an internal conduit through which cooling water can berouted through the copper tube 120. During operation of the inductionheating means 106, cooling water is directed into the copper tube 120 byway of the tube end section 124, and the cooling water exits the tube120 by way of the tube end section 126. Positioned about so as toencircle both the coil section 122 of the induction heating means 106and the passageway 112 is a protective copper magnet insert tube 130.

Although the depicted magnet 113 of the FIG. 2 embodiment 100 is asolenoid magnet having an annular core 114, magnet cores possessingother configurations can be employed. For example, an alternative magnetcan possess an oval or irregularly-shaped bore or have a bore providedwith an open end which permits, for example, the passage therethrough ofa workpiece which is in the form of a sheet.

For purposes of cooling the workpiece 102, the interior of thepassageway 112 is connected in flow communication with a source 132 ofargon purge gas and a source 134 of helium quench gas by way of a fourport chamber assembly 136 which is supported above the mounting plate118. Purge and quench gases which are directed through the passageway112 by way of the upper end of the passageway 112 are permitted to flowinto contact and around the workpiece 102 to absorb heat from theworkpiece 102 by the convective transfer of workpiece heat to the gases.The gases are thereafter permitted to flow out of the passageway 112through the lower (open) end thereof. In addition, a plurality ofthermocouples are positioned in contact with the workpiece 102 and areconnected wired to a plurality of connecting wires 138 which extend outof the chamber assembly 136 through one of the ports thereof. Theseworkpiece-contacting thermocouples can be connected to an appropriateinstrumentation (not shown) to enable the temperature of the workpiece102 to be monitored as it is being worked upon, or thermally treated,within the apparatus 100.

To enable the position of the workpiece 102 to be adjusted along thelength of the passageway 112, a quartz guide rod 140 is directeddownwardly through a port of the chamber assembly 136 and is connectedat its lower end (as viewed in FIG. 2) to the workpiece 102. The upperend of the guide rod 140 is, in turn, accessible to an operator so thatby raising or lowering the guide rod, the workpiece 102 can be movedupwardly or downwardly along the passageway 112 by a correspondingamount. Because the position of the workpiece 102 along the passageway112 can be altered, the workpiece 102 can be moved into or out ofregistry with the center of the core of the magnet 113 or into or out ofthe interior of the tube coil section 122 of the induction heating means106, as desired, during a workpiece-treatment process performed with theapparatus 100.

With reference to FIG. 3, there is illustrated an alternative embodimentof an apparatus, generally indicated 200, with which a workpiece 202 canbe worked upon, or treated, in accordance with the steps of a process ofthe present invention. The apparatus 200 includes means, indicated 204,for generating a magnetic field through which the workpiece 202 is movedand heating means 206 (i.e. induction heating means) for heating theworkpiece 202. In addition, there is included a passageway-definingmeans 210 providing a passageway 212 through which the workpiece 202 isadvanced (e.g. between the passageway entrance end 211 and a passagewayexit end 213) as it is worked upon by the apparatus 200.

Within the depicted FIG. 3 apparatus 200, the magnetic field-generatingmeans 202 includes a magnet 214 having a core 215 provided between theillustrated cross-sectional portions 216 and which is capable ofgenerating an ultrahigh magnetic field within the core 215. Thepassageway 212 is oriented horizontally and is supported substantiallycentrally within the magnet core 215 by way of a pair of spacednon-magnetic mounting flanges 217, 219, and the induction heating means206 includes a copper tube 220 having a coil section 222 which encirclesa section of the passageway 212 disposed within the magnet core 215 andhas end sections 224 and 226 which are connected to a source 227 of RFpower. In addition, the copper tube 220 defines an internal conduitthrough which cooling water from a source 229 can be routed through thecopper tube 220. During operation of the induction heating means 206,cooling water is directed into the copper tube 220 by way of the tubeend section 224, and the cooling water exits the tube 220 by way of thetube end section 226. Positioned about so as to encircle both the coilsection 222 of the induction heating means 206 and the passageway 212 isa high-frequency RF shield tube 230.

As shown in FIG. 3, the coil section 222 of the induction heating means206 is positioned adjacent the passageway entrance end 211. It will beunderstood, however, that the coil section 222 can be located along thepassageway 212 wherever it may be required so that a desired heatingcurve is generated for the workpiece 202. Furthermore, the configurationof the coil section 222 could span from the passageway entrance end 211to the passageway exit end 213. In addition, multiple coils can bepositioned about several sections of the passageway-defining means 210to create several heating zones therealong. Further still and dependingupon the size of the workpieces and the thickness of the active regionof the magnetic field-generating means 204, multiple workpieces could betreated along the passageway 212 at the same time. As is the case withthe apparatus 20 of FIG. 1 and the apparatus 100 of FIG. 2, quenchgases, such as a combination of helium and hydrogen, can be directedinto contact with selected regions of the workpiece 202 desired to berapidly cooled.

The depicted apparatus 200 of FIG. 3 is suitable for working upon, ortreating, a workpiece, or workpieces, fed either intermittently orcontinuously through the passageway 212. Within the illustrated FIG. 3example, the workpiece 202 is in the form of a length of steel wirewhich is fed through the passageway 212 from a feed roll 250 mountedadjacent the passageway entrance end 211 and wound about a take-up roll252 mounted adjacent the passageway exit end 213. It will be understoodthat as the (wire) workpiece 202 is advanced through the passageway 112,it is exposed to the generated magnetic field as it passes through thecore 215 of the magnet 216 and is heated by the induction heating meansas it passes through the interior of the coil section 222. Hence, themicrostructure of the (wire) workpiece 202 is effected by both thegenerated magnetic field and the heat-treatment of the induction heatingmeans 206. It will also be understood that the microstructure of the(wire) workpiece 202 can be altered to varying degrees by changingvariables of the treatment process, such as the strength of thegenerated magnetic field, the strength of the current directed throughthe coil section 222 of the induction heating means 206 or the rate atwhich the wire 202 is advanced through the passageway 212.

With reference to FIG. 4, there is schematically illustrated yet anotherembodiment, generally indicated 300, of an apparatus, with which aworkpiece 302 can be worked upon and attending control equipment,described herein, for controlling the operation of the apparatus 300.The apparatus 300 includes a series of stations, described herein,through which the workpiece 302 is advanced as it is moved through theapparatus 300 and at which a sequence of treatment processes are carriedout upon the workpiece 312. More specifically, the depicted apparatus300 includes three such treatment stations—one station 360 of which is apreheating station (at which the workpiece 312 is pre-heated), a secondstation 362 at which the workpiece 312 is exposed to a magnetic fieldand is also heated and cooled, and a third station 366 at which theworkpiece 312 is exposed to both heat-treatment and a cooling treatment.

For providing heat treatment at each of the stations 360, 362 and 364,there is provided induction heating means, generally indicated 358,including an induction heating coil (not shown) having an interiorthrough which the workpiece 312 is advanced as it is advanced throughthe corresponding station 360, 362 or 362. Associated with each of theheating means 358 of the stations 360, 362 and 364 is an induction drivetransformer 366 and an induction power source 368 for powering theheating coil of the corresponding heating means.

For generating a magnet field at the second station 362, the apparatus300 includes a magnet 370 for generating a ultrahigh magnetic field atthe second station 362 so that as the workpiece 302 is advanced throughthe second station 362, the workpiece 302 is exposed to the generatedmagnetic field.

To enable the workpiece 302 to be cooled or quenched at each of thesecond and third stations 362 and 364 gas, there is provided a source372 of cooling gas which is connected in flow communication with thestations 362 and 364 so that when desired, the gas is directed into thecorresponding station 362 or 364 for cooling the workpiece 302 movingtherethrough.

For controlling the various treatment operations at the stations 360,362 and 364, the apparatus 300 further includes a control computer 374which can be pre-programmed to initiate the operation of the varioustreatments of the workpiece 302 as it moves in sequence through thestations 360, 362 and 366. In this connection, there is associated withthe control computer 374 control circuitry 378 for controlling theoperation of the heating means at the various stations 360, 362 and 364,control circuitry 380 for controlling the operation of the magnet 370 atthe second station 362, and control circuitry 382 for controlling thedelivery of the cooling gas from the supply 372 to the second and thirdstations 362 and 364.

During operation of the apparatus 300, when the computer 374 determines(through pre-programmed information) that the workpiece 302 should beexposed to the desired treatment (e.g. heat-treatment, cooling-treatmentor magnetic field treatment) as the workpiece is advanced through thevarious stations 360, 362 and 364, appropriate command signals are sentfrom the computer 374 to the appropriate control circuitry 378, 380 or382 so that the desired treatment is initiated at the correspondingstation 360, 362 or 364. Appropriate feedback information (e.g. thetemperature at various points of travel through the stations 360, 362and 364 or of the workpiece itself) can be collected (through, forexample, the use of thermocouples or radiation emission) for use by thecomputer 374 so that the processes performed with the apparatus 300 canbe appropriately monitored.

It follows from the foregoing that an apparatus and process has beendescribed for altering the structural characteristics of a workpiecewhich includes an electrically-conductive material. Such an apparatusand process involves the generation of a magnetic field within which aworkpiece is positionable and the thermal treatment of the workpiece inconjunction with the generated magnetic field so that the structuralcharacteristics of the workpiece are effected by both the generatedmagnetic field and the thermal treatment.

That the microstructure of workpieces can be altered by theaforedescribed apparatus and process has been verified throughexperiments. For example, there are provided in FIGS. 5 and 6 photos ofthe cross section of samples of 52100 steel which have been annealed at950° C. for twenty minutes, then cooled to 740° C. and held at thattemperature for five minutes, and followed by a quench to roomtemperature. The FIG. 5 sample was not exposed to any magnetic fieldduring treatment, but the FIG. 6 sample was exposed to a magnetic fieldduring treatment and, in particular, to a magnetic field which wasramped to 30 Tesla at the outset of the stage of treatment at which thesample was maintained at 740° C. The magnetic field strength wasthereafter maintained at the 30 Tesla level for the duration of theexperiment.

The FIG. 5 and FIG. 6 photos are light micrographs of the microstructuretaken at about the mid-length of the longitudinal plane for eachcorresponding sample. It can be observed from the FIG. 5 photograph (byone skilled in the art) that within the workpiece sample which was notexposed to a magnetic field during the treatment thereof, some cementiteformed along prior austenite grain boundaries during the isothermalhold. However, the bulk of the microstructure of the FIG. 5 sampleremained austenitic and transformed to martensite during the subsequentquench to room temperature. In contrast and as can be observed from theFIG. 6 photograph that within the workpiece which was exposed to themagnetic field during the treatment thereof, the austenite transformedto pearlite during the isothermal hold. It therefore follows that theexposure of the workpiece to the magnetic field during the treatmentthereof altered the characteristics of the workpiece in that themagnetic field accelerated austenite decomposition.

It will be understood that numerous modifications and substitutions canbe had to the aforedescribed embodiments without departing from thespirit of the invention. For example, although the aforedescribedembodiments have been shown and described as involving heat-treatmentsteps which are carried out with induction heating equipment, suchheat-treatment steps can be carried out by any of a number ofalternative heating means and methods. For example, a workpiece can beheated by its exposure to heated gas, resistance heating elements oreven heated liquids (e.g. oil) or solids (e.g. metal salts). The choiceof workpiece heating (and cooling) mediums can be selected, for example,based upon the rate at which heat is conducted from (or to) theworkpiece to the medium.

Further still, although the heat-treating of workpieces with theaforedescribed embodiments have been described as involving a raising ofthe workpiece temperatures to an elevated level or maintaining theworkpiece temperatures at the elevated level (i.e. isothermal holds atan elevated temperature), heat-treating can involve any of a number oftechniques for effecting the temperature of the workpiece. For example,the heat-treating of a workpiece can involve a down-quenching of theworkpiece from an elevated temperature to an intermediate temperatureand holding the workpiece at the intermediate temperature; or theheat-treating can alter the workpiece temperature along any thermaltransient path that can even include cryogenic temperature excursions.

Yet still further, although the apparatus 20 of FIG. 1 has beendescribed above as including a non-magnetic guide tube 40, it may bedesirable, in some instances, that the guide tube be comprised of adielectric material. In any event, the guide tube needs to be capable ofwithstanding the working temperatures to which the workpiece would beexposed, which, for some workpieces, could exceed 1000 degrees Celsius.

As a further alternative, the guide tube could be utilized as a heatablesusceptor which is capable of transferring heat which has been generatedwithin the guide tube to the workpiece in order to heat the workpiece.For example, by positioning the workpiece within so as to contact thewalls of the guide tube and thereafter utilize induction heating meansto heat the guide tube, heat which is generated within the guide tube isconducted to the workpiece so that the workpiece is heated indirectly,rather than directly, by the induction heating means. In this latterexample in which the guide tube can be heated by induction heatingmeans, the guide tube can be constructed of materials which are easilyheated by induction, such as austenitic stainless steels and carbon orother materials which possess a high resistivity.

Furthermore, although the aforedescribed embodiments have been shown anddescribed as involving cooling steps which involve a cooling gas, suchas argon or helium, such cooling steps can be carried out by any of anumber of alternative cooling means and methods. For example,alternative cooling fluids, such as steam (also a gas), water (a liquid)or sand (a solid) can be directed into contact with the workpiece forcooling purposes. The selection and temperature of the medium with whicha workpiece is cooled may be selected based upon the rate at which theworkpiece is desired to be cooled.

Accordingly, the aforedescribed embodiments are intended for the purposeof illustration and not as limitation.

1. A process for altering characteristics of a workpiece which includesan electrically-conductive material, the process comprising the stepsof: providing a workpiece comprising an electrically conductive materialwithin a bore of a magnet; providing, between the workpiece and themagnet, a means for thermally treating the workpiece; exposing theworkpiece to an ultrahigh magnetic field of at least one Telsa generatedby the magnet; and thermally treating the workpiece by the means inconjunction with the exposure of the workpiece to the magnetic field sothat the characteristics of the workpiece are affected by both theultrahigh magnetic field and the thermal treatment.
 2. The process asdefined in claim 1 wherein the step of thermally treating includes astep of heating the workpiece.
 3. The process as defined in claim 2wherein the step of heating is carried out with induction heatingtechniques.
 4. The process as defined in claim 1 wherein the step ofthermally treating includes a step of cooling the workpiece.
 5. Theprocess as defined in claim 4 wherein the step of cooling includes astep of introducing a cooling medium into contact with the workpiece. 6.The process as defined in claim 5 wherein the step of introducingincludes a step of directing a cooling fluid across the workpiece. 7.The process as defined in claim 6 wherein the cooling fluid directedacross the workpiece is one of a gas from a group of gases consisting ofargon and helium.
 8. The process as defined in claim 1 wherein the stepof thermally treating includes: a step of heating the workpiece; and astep of cooling the workpiece.
 9. The process as defined in claim 8wherein the step of heating the workpiece and the step of cooling theworkpiece are coordinated with one another to impart preselectedcharacteristics to the workpiece.
 10. The process as defined in claim 1wherein the bore of the magnet defines a passageway, and furthercomprising moving the workpiece through the passageway during theexposure to the ultrahigh magnetic field.
 11. The process as defined inclaim 1 wherein the ultrahigh magnetic field is at least as high as 1Tesla.
 12. The process as defined in claim 11 wherein the ultrahighmagnetic field is as high as several tens of Tesla.
 13. A process foraltering characteristics of a workpiece, the process comprising:disposing a workpiece comprising an electrically conductive materialwithin a bore of a magnet; providing a heating medium adjacent to theworkpiece; thermally treating the workpiece; exposing the workpiece toan ultrahigh magnetic field of at least 1 Tesla generated by the magnetduring the thermal treatment so as to alter characteristics of theworkpiece by both the ultrahigh magnetic field and the thermaltreatment.
 14. The process of claim 13 wherein the heating medium isselected from the group consisting of: an induction heating coil,resistance heating elements, a heated gas, a heated liquid, and a heatedmetal salt.
 15. The process of claim 13 wherein thermally treating theworkpiece comprises heating the workpiece using the heating medium andcooling the workpiece by contacting the workpiece with a cooling fluid.16. The process of claim 15 wherein the cooling occurs after theexposure to the ultrahigh magnetic field.
 17. The process of claim 13wherein the bore of the magnet defines a passageway, and furthercomprising moving the workpiece through the passageway during theexposure to the ultrahigh magnetic field.
 18. The process of claim 13wherein the magnet comprises an annular core, and the heating medium isdisposed between the workpiece and the magnet.
 19. The process of claim13 wherein the bore of the magnet has an open end.
 20. The process ofclaim 13 wherein the magnet comprises a superconductor.